LIGO Document G0900507-v2

Overview of monolithic suspension work for Advanced LIGO

The LIGO science collaboration will soon begin Science Run 6, a data gathering run using 'enhanced' detectors with an average sensitivity improvement of 2 since the previous run. In parallel, work is ongoing for a major improvement of systems for the Advanced detectors that are scheduled to be installed from ~2012. The projected improvement in strain sensitivity for the Advanced detectors is about a factor of 10. This improvement is accomplished in part by replacing the test mass mirror suspension system with a 4 stage suspension with a monolithic fused silica final stage that provides better seismic isolation and lower thermal noise. In this final stage silica interface pieces (‘ears’) are bonded to the test masses (mirrors) using the hydroxy-catalysis bonding technique and silica fibers are welded to these ears. A prototype of the full suspension system is currently being built at the LIGO Advanced Systems Test Interferometer (LASTI).
We will present an overview of the work to develop and test the lower stages of the Advanced LIGO mirror suspensions, including ear and fiber design, laser and flame welding research, and tooling developments.